Now that C++0x provides tools for compile-time computations could it
also add math functions evaluated at compile-time to the standard
library? One of the examples in N2116 shows the usage of complex
numbers:

constexpr complex I(0, 1);
constexpr double xx = I.real();

It would be useful if we could also define complex class literals with
polar coordinates:

constexpr complex = complex::polar( 0.5 * PI, 1 );
constexpr double xx = I.real();

In order to do that we would have to have a constexpr sin function.
making std::sin a constexpr is probably unrealistic, but providing a
set of math constexpr functions seams fair. Sine can be represented as
a set of additions and multiplications that meet constexpr
requirements.

Such a std::compiletime::sin might also be useful in run-time. It
would give a guarantee of a deterministic function (at the expense of
performance).

&rzej

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